What is pericardial effusion – Cardiology Basics

What is pericardial effusion – Cardiology Basics

Pericardial effusion is collection of fluid between the visceral and parietal layers of the pericardium. If the amount of pericardial fluid is large or there is a rapid increase in the amount of pericardial fluid, compression of the heart prevents its proper filling. This reduces cardiac output and causes hypotension and is known as cardiac tamponade.

Cardiac tamponade needs urgent pericardial aspiration or surgical drainage if the fluid is very thick. Very thick fluid can be there in purulent bacterial pericarditis. Sometimes it can be a hemopericardium due to bleeding into the pericardial cavity. This occurs most commonly in malignant pericardial effusion. Usually it is secondary spread of malignancy rather than primary malignancy of the pericardium or mesothelioma, which is very rare.

An important type of bacterial infection which causes pericardial effusion is tuberculosis. It may or may not be associated with tuberculosis elsewhere in the body. Tuberculous pericardial effusion can be documented by aspirating the fluid and culturing the fluid for the presence of Mycobacterium tuberculosis. After draining the pericardial fluid, tuberculous pericardial effusion needs full course of antituberculous therapy.

If the cause is a malignancy, in addition to draining the pericardial fluid, the primary malignancy has to be treated. This may include chemotherapy, radiation, and surgery, depending on the type of malignancy. Malignant spread could be from nearby organs like the lung or breast or metastasis from distant organs. Cytology of the aspirated fluid may give information on the type of malignancy. Usually other investigations to search for the location and spread like a positron emission tomography (PET scan) may be considered.

Pericarditis can present with chest pain and cause pericardial effusion. But pericardial effusion can build up slowly without much pain as well. When the quantity is large enough to compress the heart, the person may feel breathless or dizzy because of a fall in blood pressure. Sometimes mild pericardial effusion may be detected by an echocardiogram done for other causes.

Pericardial effusion is usually confirmed by an echocardiogram. In case of cardiac tamponade, the heart can be seen swinging within the large amount of fluid in the pericardial cavity. In addition, diastolic collapse of right atrium and right ventricle can be seen, interfering with diastolic filling.

ECG shows low voltage complexes in pericardial effusion. This is because the fluid surrounding the heart prevents good conduction of electrical activity of the heart to the body surface. When the heart swings in the pericardial cavity due to large amount of fluid in cardiac tamponade, alternate complexes in the ECG can be seen as taller and shorter. This is known as electrical alternans. When the P, QRS and T waves shows alternating amplitudes, it is known as electrical alternans totalis.

In addition to malignancy and tuberculosis, any other cause of pericarditis can also cause pericardial effusion. Viral infection is an important cause of pericarditis and pericardial effusion. Bacterial infections in the adjacent organs like lungs can also rarely spread to the pericardium, causing pericarditis.

Pericarditis can occur after a myocardial infarction. When it occurs as a post myocardial infarction complication, it is known as Dressler’s syndrome. Immunological disorders can also cause pericarditis and pericardial effusion. Radiation treatment given for malignancy of adjacent organs like lungs and breast can also cause pericarditis. Rheumatic fever is another important cause of pericarditis. But a large pericardial effusion is uncommon in rheumatic fever, where the involvement is mainly of the heart valves. Infective endocarditis can also spread to the pericardium and cause pericardial effusion.

Another important cause of pericardial effusion is hypothyroidism. Though hypothyroidism is very common in the community, pericardial effusion due to hypothyroidism is very rare. This is probably because of prompt detection of hypothyroidism due to readily available thyroid function tests and early treatment, unlike in the past. Hence, they seldom become severe enough to develop pericardial effusion. Treatment of hypothyroidism is also not very expensive and needs only thyroxine replacement.

Importance of pericardial effusion is the need for prompt treatment in those who develop cardiac tamponade, which is a potentially life threatening condition. Mild pericarditis with minimal pericardial effusion need only medical treatment and follow up. In case of diseases like tuberculosis or other bacterial infection, long term follow-up is needed. This is because some of them may develop constrictive pericarditis. In constrictive pericarditis, a thickened pericardium can prevent proper diastolic filling and needs early pericardiectomy. If there is a delay, pericardium becomes calcified and pericardiectomy can damage coronary arteries.